Data from 2010

Water Budgets and Water Table Data – 2010. The continuous monitoring of lake levels, wetland water tables, precipitation and evaporation with embedded sensors began during April in Trout Bog and during May in Crystal Bog. Monitoring ended in early November. Over this time period, data were collected at 15 to 30 minute time intervals, except for precipitation which was monitored on an event basis (0.25 mm per event). In Trout Bog, the lake level node malfunctioned until mid-July, so manual staff gauge readings were made periodically to track changes in lake level.

Comparative water budgets for the two wetland-dominated lakes (below) indicate that water levels declined until early June due to low precipitation and relatively high rates of evaporation. During the unusually warm and dry spring, net seepage was zero or negative – indicating that the predominant flowpath was from the lake into the wetland. For Trout Bog, this flowpath dominated for most of the year even though rainfall was unusually high from June to November. However, there were several abrupt (and short-lived) flowpath reversals associated with heavy rainfall events in July, August and September. In contrast, the dominant flowpath in Crystal Bog was from the wetland to the lake during most of June and July. Consistent with this flowpath, CDOM sensors in the lake indicated a gradual increase in the DOC content of CB lakewater during this period. When the CB flowpath reversed in late July, CDOM reached a plateau.

Overall, direct precipitation was by far the dominant source of water for both lakes, and evaporation back to the atmosphere was the dominant loss process. Evaporation rates were ~30% higher, on average, in CB than TB – perhaps due to higher water temperatures (average depth < 2m vs. ~6m in TB) and less tree cover along the shoreline (i.e. greater fetch). In general, both lakes tended to lose water to the adjacent wetlands.

Water table data from sensors embedded in wetland piezometers were consistent with water budgets for the lakes.